The Angels Camp City Council on Tuesday will discuss the need for emergency backup water supply.

An October 2011 audit of the city’s water system identified improving the emergency supply as one of the most important upgrades needed. The city has a single water source, the Utica Power Authority Angels Creek system, and a 30-day backup supply at Ross Reservoir about three miles up from the Angels Forebay. The city remains susceptible to an interruption downstream for the forebay, according to consultants from Stetson Engineers in San Rafael.

The city’s water system has proven vulnerable in the past. The 2001 Darby Fire destroyed a quarter-mile section of wooden flume and required temporary overland piping and pumping of water from an abandoned mine shaft to meet residents’ needs.

Constructing one or more wells or setting up a permanent pumping system from one of the mines are among the recommendations developed in the audit report.

The workshop will begin at 5 p.m., an hour before the regular scheduled meeting.

Items on the regular agenda include approval of a new joint powers authority for the Central Sierra Economic Development District, which includes the counties and incorporated cities of Tuolumne, Calaveras, Mariposa, Alpine and Amador counties. It allows the region to pursue certain federal grants for economic development. The new JPA amends bylaws to make it easier to establish a quorum and act on agenda items, which has sometimes proven difficult when many of the 13 members must drive hours to the monthly meeting.

The council will also select from among its members delegates to various JPAs, including CSEDD, the Utica Power Authority and the Calaveras Council of Governments, a transportation policy-making body. Interim City Attorney Derek Cole is also scheduled to address Brown Act public meetings law training for the council, which includes two new members sworn in on Jan. 8.